Machine for bending plate sections

ABSTRACT

A machine for bending plate sections such as bumpers for vehicles, by means of rollers pushed against the piece of section being worked, mounted on a mandrel, wherein the mandrel is mounted movable in translation upon a support member pivotally connected to the structure of the machine, and the rollers are pushed by respective cylinders according to a fixed direction approximately directed towards the rotation axis of the support member carrying the mandrel.

Enited States Patent [191 Zaramella Sept. 24, 1974 MACHINE FOR BENDING PLATE SECTIONS [75] Inventor: Gian Carlo Zaramella, Torino, Italy [73] Assignee: O.M.1P. Officine Meccaniche Ponti &

C.s.n.c., Torino, Italy [22] Filed: Mar. 13, 1973 [21] Appl. No.: 340,753

[52] US. Cl. 72/153, 72/384 [51] Int. Cl B2ld 7/04 [58] Field of Search 72/153, 149, 381, 387, 72/384 [56] References Cited UNITED STATES PATENTS Green 72/153 3,276,235 l0/l966 Stanley 1. 72/149 Primary ExaminerCharles W. Lanham Assistant Examiner-Robert M. Rogers Attorney, Agent, or Firm-Young & Thompson [57] ABSTRACT A machine for bending plate sections such as bumpers for vehicles, by means of rollers pushed against the piece of section being worked, mounted on a mandrel, wherein the mandrel is mounted movable in translation upon a support member pivotally connected to the structure of the machine, and the rollers are pushed by respective cylinders according to a fixed direction approximately directed towards the rotation axis of the support member carrying the mandrel.

6 Claims, 6 Drawing Figures MACHINE FOR BENDING PLATE SECTIONS BACKGROUND OF THE INVENTION The present invention relates to improvements in machines intended to perform, by rolling, the bending at a constant or variable radius of plate sections, particularly bumpers for vehicles.

As is known, the bumpers for vehicles, and similar objects, are usually manufactured by first forming or bending a piece of plate in accordance with a desired profile, and then rolling the thus obtained piece of section upon a mandrel for imparting to it the desired shape. Such rolling operation is performed by means of machines wherein the mandrel is pivotally mounted and is rotated while a pair of forming rollers, which are carried by a swingable support and are pushed by a hydraulic cylinder towards said mandrel, slide on the piece of section arranged on the mandrel, thereby rolling the same. These machines have various disadvantages which on the one hand render imperfect the operation of the machines and on the other hand require a strong actuating power to be used; said disadvantages primarily arise from the fact that the shape which has to be imparted to the workpiece is often very different from a circle and consequently, even when choosing in the best possible way the pivotal center of the mandrel, great variations of the lever arm on which the mandrel cooperates with the rollers take place during the operation, and also great variations of the angle at which the pair of rollers have to be arranged in order to match with the shape of the mandrel. In order to reduce these disadvantages it has been suggested to mount the forming rollers, with their swingable support and the actuating cylinders, on a carriage movable in translation perpendicularly to the direction of the pressure exerted by the rollers. Such an arrangement does not avoid completely said disadvantages, since the direction of the pressure exerted by the rollers is not constantly directed towards the pivotal center of the mandrel; and moreover it entails on the other hand a very complex and expensive structure, as well as large overall dimensions of the machine.

BRIEF SUMMARY OF THE INVENTION The object of the present invention is to improve a machine of the specified general type, by rationalizing its operation in such a way as to achieve the best operative results by using relatively moderate force. This object is attained, according to the invention, primarily by the fact that the mandrel is mounted to be movable in translation upon a support member which in turn is pivotally connected with the structure of the machine, whereas the forming rollers are pushed by the respective cylinders in a fixed direction. In this way, the movement of the mandrel results from a combination of translation and rotation, and either by producing said movements in a succession or by accomplishing them simultaneously at least during a part of the travel, it is possible to ensure that the forming rollers act against the section being worked, which bears against the mandrel, always in the most rational and suitable position and condition. Furthermore, preferably, the forming rollers are not mounted on a swinging support and are not pushed collectively by an actuating cylinder, as in the known machines, but they are loaded independently from each other by separate cylinders, so that each of the rollers acts on the workpiece without any interdependency in respect of the action of the other roller. Thus, it is also possible to adjust in a different way the pressures exerted by the two rollers in the various stages of the work, and even to render inoperative one of the rollers at particular areas of the workpiece.

According to a further improvement, the rotation of the pivoted support member which carries the translatable mandrel is preferably controlled by means of chains or wire ropes anchored on a drum and controlled by hydraulic cylinders. When ropes are used, provision is made for a particular manner of anchoring the ropes on the drum, which ensures the best conditions of operation at the high loads which have to be expected.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be illustrated in a more detailed way in the following description of an illustrative and non limitative embodiment, diagrammatically shown in the accompanying drawings, wherein:

FIG. 1 shows a longitudinal vertical section through the machine, substantially in the area of the rotation axis of the mandrel support member;

FIG. 2 is a horizontal section thereof, substantially taken along line II-II of FIG. 1;

FIGS. 3 to 5 diagrammatically show the operative parts of the machine in three successive operation stages;

FIG. 6 shows the anchorage of the ropes which control the rotation of the support member of the translatable mandrel.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT.

The structure of the shown machine comprises primarily an upper plate 1, a base plate 2, side plates 3 and an end plate 4. Mounted within bearings 5, 6 carried by the upper and base plates 1, 2 there are vertical pivots 7, 8 of a support member 9 which is thus rotatable about a vertical axis A. Connected to the pivot 7 is a drum 10 on which are wound and anchored two chains or two wire ropes l1, l2 terminating on pulleys l3, 14 mounted on rods 15, 16 which are actuated by hydraulic cylinders 17. This arrangement allows rotating the support member 9 in the desired direction about said axis A.

On the support member 9 is slidably mounted, on guides 18 perpendicular to the axis A, a bench 19 adapted to receive, in a well known manner, a mandrel 20 serving for shaping a piece to be wrought, for example a bumper P. Connected at 21 to the support member 9 is a hydraulic cylinder 22 whose piston rod 23 is connected to the bench 19; this arrangement permits to impart to the bench 19 with the mandrel 20 a translation motion in the desired direction relative to the support member 9.

Two forming rollers 24, having a well known shape, are each pivoted idly on a ram 25 slidable along guides 26 between the plates 1 and 2 of the structure of the machine substantially in a direction towards the axis A. Each ram 25 is connected to the piston rod 27 of a hydraulic cylinder 28. This arrangement allows one to put each roller 24 in contact with the workpiece P mounted on the mandrel 20 and to push with a suitable force against the workpiece, which force may be chosen independently for the two rollers 24.

The operation of the machine is as follows:

After having arranged the machine in such a way that the direction of the translation of the bench 19 relative to the support member 9 is approximately perpendicular to the movement direction of the rollers 24, the workpiece P is mounted on the mandrel 20. For the sake of clarity, the workpiece P is shown in FIGS. 2 to as already shaped in accordance with the mandrel 20, i.e. as results after the work has been completed. Actuation of the cylinders 28 carries rollers 24 against the workpiece P and pushes them with forces F1 and F2. The configuration shown in FIG. 3 is obtained. By actuating then the hydraulic cylinder 2, the bench 19 with the mandrel and the workpiece P is moved in the direction of the arrow F3, and the machine passes, through the configuration shown in FIG. 2, to the configuration shown in FIG. 4. At this stage, the rollers 24, being pushed by the forces F1 and F2, effect the rolling operation on the part of workpiece P having the least curvature.

Once the configuration shown in FIG. 4 is obtained, actuation of one of the hydraulic cylinders 17 (while the other serves as brake) causes the support member 9 to rotate in the direction of arrow F4, together with the bench 19, the mandrel 20 and the workpiece P, towards the configuration shown in FIG. 5 and even beyond it, while the rollers 24 roll the part of greater curvature of the workpiece P up to its end.

This transition between a stage of translation in the direction of arrow F3 and a stage of rotation in the direction of arrow F4 may, of course, be replaced by a combination of the two motions, and more generally it is possible to have a first stage of translation only, a second stage of simultaneous translation and rotation and a third stage of rotation only. During these three stages, the force F1, respectively F2, with which the rollers 24 are pushed against the workpiece P, can be adjusted independently for each of the two rollers, in accordance with a program suitable to achieve the best results. In any case, the resultant of the rolling forces, applied to mandrel 20, bench l9 and support member 9, present a moderate lever arm with respect to the axis A and consequently it does not load excessively the rotational system of the support member 9, which requires an actuation only with a moderate power. Torque inversions, which may occur in correspondence with particular points of some shapes, are absorbed by the braking action exerted by one of the cylinders 17, thus ensuring a regular performance of the rotational movement.

The operations of mounting the workpiece P on the mandrel, removing said workpiece after the described operation has been completed, re-mounting said workpiece in an inverted position and working its opposed part, take place in the usual manner, well known for such kind of machines, and do not require to be described particularly herein. Also it is obvious that the mandrels 20 mounted on the bench l9, and consequently the profiled grooves of the rollers 24, may be more than one to allowsimultaneous work on plural pieces.

Since, in the presence of high stresses, such as those required to produce the rotation of the drum 10, the anchorage of the traction ropes ll, 12 (in case chains are not employed) to said drum would present problems, according to a particular aspect of the invention said ropes are of wire and pass around separate pairs of grooves on the drum l0 and are anchored in arcuate return grooves, respectively 1011 and 10b, provided between the respective grooves of the drum. The arcuate grooves are made deep enough to allow coupling of the respective portions of ropes, and the groove 10a is made deep up to below the bottom level of the circumferential grooves, as shown in FIG. 6 so as to allow overlapping of the portions of different ropes, as occurs in certain positions as shown in FIG. 1, without establishing any contact between the overlapping ropes and consequently without any abnormal stress applied to them.

The arrangements and the embodiments described and illustrated herein are given only by way of example and can be replaced by various technical equivalents. Thus, for instance, although the described independent arrangement of the rollers 24 is preferred, in certain cases the usual arrangement may be used in which the two rollers are carried by a support member adapted to swing, pushed by a single hydraulic cylinder. The guidance of the rollers 24 can be obtained in various ways. Also the configuration of the pivotal support member 9 and the bench 19 carrying the mandrel can be varied, as well as the arrangement of the hydraulic cylinder 22 acting to control the mutual displacements. Finally, the control of the rotation of the support member 9 by means of chains or ropes wound on a drum is preferred because it allows a more ample angle of rotation, but it is in no way limitative.

Having thus described my invention, what I claim is:

1. A machine for bending plate sections, comprising a stationary structure, a rotatable support member mounted on said stationary structure for rotation about a first axis which is fixed relative to said stationary structure, first drive means operatively connected to said structure and to said support member for rotating said support member about said fixed axis, a shiftable bench mounted on said support member for movement relative to said support member in a direction perpendicular to said pivot axis, second drive means connected between said support member and said bench for moving said bench relative to said support member in said perpendicular direction, a shaped mandrel mounted on said bench for receiving thereon a plate section to be bent, at least one rotatable forming roller mounted on said structure for movement toward and away from said mandrel, and third drive means operatively connected between said structure and said at least one forming roller for pushing said forming roller toward said mandrel and plate section mounted thereon whereby said mandrel and plate section perform relative to said at least one forming roller operative displacements comprising translation relative to and rotation about said first axis.

2. A machine as claimed in claim 1, said at least one roller being mounted for rotation about a second axis parallel to said first axis.

3. A machine as claimed in claim 1, there being two said rollers mounted on said third drive means for rotation about parallel axes.

4. A machine as claimed in claim 3, said two axes moving in planes parallel to and disposed equal distances on opposite sides of the said first axis.

5. A machine as claimed in claim 1, said first drive means comprising a drum connected to said support member, said drum having peripheral grooves and deep arcuate return grooves, and wire ropes anchored within means acting along a line of force that is perpendicular to and spaced from said first axis and disposed between said first axis and said at least one roller. 

1. A machine for bending plate sections, comprising a stationary structure, a rotatable support member mounted on said stationary structure for rotation about a first axis which is fixed relative to said stationary structure, first drive means operatively connected to said structure and to said support member for rotating said support member about said fixed axis, a shiftable bench mounted on said support member for movement relative to said support member in a direction perpendicular to said pivot axis, second drive means connected between said support member and said bench for moving said bench relative to said support member in said perpendicular direction, a shaped mandrel mounted on said bench for receiving thereon a plate section to be bent, at least one rotatable forming roller mounted on said structure for movement toward and away from said mandrel, and third drive means operatively connected between said structure and said at least one forming roller for pushing said forming roller toward said mandrel and plate section mounted thereon whereby said mandrel and plate section perform relative to said at least one forming roller operative displacements comprising translation relative to and rotation about said first axis.
 2. A machine as claimed in claim 1, said at least one roller being mounted for rotation about a second axis parallel to said first axis.
 3. A machine as claimed in claim 1, there being two said rollers mounted on said third drive means for rotation about parallel axes.
 4. A machine as claimed in claim 3, said two axes moving in planes parallel to and disposed equal distances on opposite sides of the said first axis.
 5. A machine as claimed in claim 1, said first drive means comprising a drum connected to said support member, said drum having peripheral grooves and deep arcuate return grooves, and wire ropes anchored within said grooves of the drum at one end and reeved about pulleys, and hydraulic piston and cylinder units connected between said pulleys and said stationary structure.
 6. A machine as claimed in claim 1, said second drive means acting along a line of force that is perpendicular to and spaced from said first axis and disposed between said first axis and said at least one roller. 